Earth auger



ma ma F. E. REED EARTH AUGER Why M a";

Filed March 5, 1951 JIVVENTOR.

Fmnnssv E. REED BY I United. States Parent 6 EARTH AUGER Forrest E.Reed, Bellevilie, ill.

Application March 5, 1951, Serial No. 213,902

1 Claim. (Cl. 255-69) This invention pertains to earth angers such asare used to (ig post holes for telephone poles and the like.

Generally stated, the invention involves improvements in the bit whichis formed with a pair of i'lights armel at their Cutting ends withhardened renewable cutters of improved shape, and a fish-tail tip orpilot cutter which is also renewable. The tip is secured to the body ofthe bit in a novel manner so as to be supported against side strainstending to break oil the tip.

An illustrative embodiment of this invention is shown in theaccompanying drawing, in which Fig. l is a side vi w of an auger bitembodying this invention, with part in section, the bit being shown ininverted position relatively to that assumed when in use;

2 is a top end view of Fig. 1;

Fig. 3 is a detail section on line 3-3 of Fig. 1;

Fig. 4 is a bottom view of Fig. 1, showing the mounting socket of thebit, to a reduced scale.

Referring to the drawing, the body of the bit com prises a steel castingformed with an axial shank l and two flights 2 extending radially inopposite directions from the shank 1. The forward end of the shank 1 hasremovably mounted therein, as by a threaded shank 3, a pilot tip 4 whichmay be a steel casting of fish-tail form having hardened cutting flights5. In view of the fact that Fig. 1 shows the auger bit in invertedposition, that is, with its tip up, while in use of course, the tipextends downward, and the terms top and bottom. upper and lower will beused to refer to the device in the position it is in use when digging ahole; that is, with the tip down. Also the terms forward and rearwardrefer to directions of movement, the forward movement of the bit as awhole being downward as it digs, while the forward direction of rotationis clockwise, as seen from above the bit when in use.

Each of the flights 2 is provided at its forward or entering end with arenewable cutter 6. This cutter is secured to the flight by bolts 7, orother suitable fastenings so as to extend in continuation of the flightand suw stantially in alinement with the end portion thereof to which itis attached, as shown in Figs. 1 and 3. Each cutter 6 is hardened alongits cutting edge so that it may have a long life between replacements.The upper face of the cutter is also formed with a concave surface asindicated at 8 (Fig. 3).

The flights 2 are formed with a pitch which increases progressively fromthe front end to the rear end of the bit. This also provides forgradually increasing the velocity of movement of the cut material andprovides increasing volume between the flights as the material becomeslooser in its movement back along the bit. The outer edges of theflights 2 are also hardened, so as to withstand the wear incident to theboring operation.

Great difiiculty has been experienced heretofore in mounting a tip, suchas 4', so as to be safe against breakage. When the tip strikes a hardrock displaced laterally from the axis of the hole being bored, the sidestrain often breaks oil the shank 3. In accordance with this invention,therefore, the threaded shank 3 of the tip threaded into a socket 19 inthe body of the bit. The

terminal opening of this socket is bored smooth for a short distance andthe shank 3 is formed with a collar ii at its junction with the tip 4.This collar 11 is fitted to the bore of said terminal opening closelyenough to require a definite, though moderate pressure to force it intosaid bore. It may be given a slight taper. When assembled. it is screwedin against such pressure until the face ill. of the tip contacts firmlywith the engaging face ot the body. When so seated, the end bore of thesocket ltl provides a lateral support for the collar 11 to absorb sideshocks and prevent them from being transmitted to the threaded portionof the shank 3. The thread of the shank may be terminated short of theroot of the shank (where it joins the tip 4) as shown at 3a in 1 so thatstresses due to such side shocks are removed from the terminus of thethread which is usually the weakest part of the shank.

The upper end of the body shank l is formed with a mounting socket 13,usually angular in form, to receive the driving element of the boringmachine. A transverse hole 14 may be provided to receive a cross pin forretaining the bit in place. Most machines provide a spring on thisdriving element against which the bit strikes when elevated to the limitof its travel, the impact serving to dislodge the dirt from the bit. inorder to take this impact the present invention provides that theflights 2 are continued to the upper end of the socket 13, their endsbeing flush with the ends of the socket. The webs of the flights arealso thickened where they join the wall of the socket as indicated at15. This provides a broadened surface of metal, symmetrical about thebit axis, to take the impact.

it will be seen, therefore, that this invention provides an anger whichis inexpensive. though sturdy, and which can be maintained in goodworking condition with little trouble or expense. The renewable cuttersof special shape are quickly changeable when worn. Their shape and thatof the flights is such as to remove the earth easily and with a minimumexpenditure of power.

Various changes may be made in the details of construction, within thescope of the appended claim, without departing from the spirit of thisinvention. Parts of the invention may be used without the whole andimprovements may be added while retaining some or all of the advantagesof this invention.

I claim:

An earth auger comprising, a body formed with a central shank, a pair ofoppositely extending helical flights integral with an progressing alongsaid shank, said shank being formed with a threaded tip receiving socketat its lower end and a mounting socket at its upper end, a pilot tip, ashank on tip threaded to fit said threaded socket and having asupporting collar at its junction with said tip, said collar beingfitted to a pressure fit with the bore of the terminal openin of saidtip socket, each of said flights having a pitch increasing progressivelyfrom its entering end rearward, 3.: a renewable cutting bit detachablymounted on the entering end of each of said flights.

References Cited in the tile of this patent UNITED STATES PATENTS 76.188Heath Mar. 31, 1868 558,994 Snyder Apr. 28, 1896 1,376,224 Paszko Apr.26, 1921 1,466,378 McLaughlin Aug. 28, 1923 1,849,510 Thomson Mar. 15,1932 2,201,159 Clow May 21, 1940 2,239,461 Mann Apr. 22, 1941 2,613,062Herbert Oct. 7, 1952 FOREIGN PATENTS 248,839 ltaly June 18, 1926

